1. Field of the Invention
The present invention concerns circuitry for controlling current in order to control the response time of electromagnetic devices having a solenoid to drive the electromagnetic injectors of an injection system for internal combustion engines. This control is realized using reference voltage sources which determine different levels of the driving current of the solenoid.
2. Description of the Prior Art
The problem posed by the control of solenoids, particularly fast-acting ones such as the electromagnetic injector solenoids of an internal combustion engine injection system, is to control the electrical response time of the solenoid command.
Arrangements are known for controlling solenoids with regulated command voltage, but these arrangements do not permit obtaining constant driving currents since they do not compensate for variation in coil resistance during temperature changes.
There are also known controls with constant current which are much less expensive than those with constant voltage and which allow control of the magnetic force exerted by the solenoids in the steady state. However, such controls do not permit obtaining an electrical response time independent of the supply voltage of the control electronics, thus requiring the regulation of the supply voltage.